<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="utf-8" />
    <title>隐藏域</title>
</head>

<body>
    <form action="#" method="get">
        搜索<input type="text" name="key">
        <br>
        <input type="hidden" name="act" value="input">
        <input type="submit" value="提交数据">
    </form>
</body>

</html>